iPhone and iPads Retina use the same coordinate system as non-retina devices. Currently, all iPads have a 768x1024 logical coordinate space, and all iPhones, except the iPhone 5, have a 320x480 logical coordinate space. Your code should work well on Retina and Non-Retina devices.
iPhone 5 , iOS, , Default.png .
[[UIScreen mainScreen] bounds]. Retina Retina. Retina, [[UIScreen mainScreen] scale]; - (1.0 Retina, 2.0 Retina).